Large scale earth grading operations are typically carried out using specialized motor graders which tend to be large and expensive. On large construction projects, such as large housing tracts, highway construction, and the like, the use of such specialized graders can be justified in terms of size and efficiency. However, on smaller construction projects, the cost of transporting a large motor grader to a site and operational costs are inappropriate for the size of the job. Such smaller projects may include construction of smaller roads, contouring of farm land, landscaping for individual house construction sites, and the like.
For this reason, various types of smaller scale earth grading equipment have been developed which can be connected or hitched to general purpose work vehicles such as dozers, loaders, and agricultural type tractors. Such an approach requires a much lower investment in the grading equipment, and the vehicle to which it is connected can be utilized for other purposes. Smaller scale grading apparatus generally includes a curved scraper blade mounted on a supporting frame which can be lowered into soil engagement and raised for movement between areas to be graded and for transport to and away from the construction site.
There are various advantages and disadvantages to locating the grader blade in front of the prime mover vehicle or behind the vehicle. An advantage of locating the blade in front of the vehicle is that a push blade provides generally better visibility since the operator only needs to look in a forward direction. A disadvantage of a front location of the blade is that imprints of the tires or tracks of the vehicle are usually left in the graded soil. With a rear located or drawn blade, the attention of the operator is divided between looking forward to properly steer the vehicle and for safety and looking backward to monitor the grading operation. However, with a drawn type blade, any impressions left by the draft vehicle are usually graded away by the blade.
It has been observed that grading operations using a transversely oriented scraper blade which is drawn tend to create a shallow rippling effect on the soil surface. Such undesirable rippling may result from changes in the working angle of the scraper blade as the tires of the draft vehicle follow the original contours of the soil surface to be graded.
Modern agricultural tractors have increased in size and in drawing power as the width and depth of agricultural soil working tool frames have increased. Increases in the width and depth of such tool frames have occurred to increase the area worked per unit of length travelled by the tractor and to perform multiple soil working operations with different sets of soil working tools in a given pass over the field. Because such agricultural tool frames must often be transported over roads and highways to and from the work site, vehicle width limits on such roads have resulted in the development of configurations of agricultural tool frames which can be reduced in width, such as by folding up wing sections of such frames. While, folding wing configurations of pushed grader blades have been developed, types of drawn grader blades which are known are limited in width to that which can be legally transported on roads or types which must be disassembled to avoid excessive width during transport.